Understanding the impact of support materials on CoFe₂O₄ catalyst performance for hydrogen fuel and nanocarbon production via methane decomposition

This study focuses on assessing the performance and durability of three distinct catalysts, namely CoFe₂O₄/MgO and CoFe₂O₄/TiO₂ and CoFe₂O₄/Al₂O₃ in the methane decomposition process. These catalysts were synthesized using a co-precipitation impregnation route. Their catalytic activity of methane decomposition was examined in a fixed-bed reactor at a temperature of 800 °C under atmospheric pressure. Various appropriate analytical techniques were employed to explore the physicochemical characteristics of both the fresh and spent catalysts. The SEM images, XRD and H₂-TPR results of fresh catalysts revealed strong dependence on the support type. The XPS results confirm the presence CoFe₂O₄ species on the surface of supports. The CoFe₂O₄/MgO catalyst has a higher inversion degree compared with other catalysts as confirmed from Raman results. The methane conversions at the end of the reaction time (300 min) were found to be 66 %, 34 % and 2.48 %, while the rates of hydrogen formation corresponding to these methane conversions are 134.73 × 10⁻⁵, 68.25 × 10⁻⁵ and 8.80 × 10⁻⁵ mol H₂ g⁻¹ min⁻¹ for CoFe₂O₄/MgO and CoFe₂O₄/TiO₂ and CoFe₂O₄/Al₂O₃ catalysts, respectively. SEM images verified the existence of filamentous carbon on the surface of the spent CoFe₂O₄/MgO catalyst, whereas the spent CoFe₂O₄/TiO₂ catalyst showed a mix of carbon chunks and filaments and fluffy carbon over the CoFe₂O₄/Al₂O₃ catalyst. Ultimately, the quantity of deposited carbon was significantly associated with catalytic activity, as they were 56, 46 and 4 wt% for the spent CoFe₂O₄/MgO, CoFe₂O₄/TiO₂ and CoFe₂O₄/Al₂O₃ catalysts, respectively.